JP2011161032A - X-ray ct scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT scanner that correctly indicates a scanning region even if a subject changes in thickness. <P>SOLUTION: In the X-ray CT scanner that comprises the top to carry a subject on, an X-ray tube for irradiating X-ray to the subject, and an X-ray detector disposed facing the X-ray tube and comprising a plurality of X-ray detection elements arranged in a plurality of rows, the scanner includes a collimator provided between the X-ray tube and the detection elements and obstructing the X-ray at least partially, a collimator driving means to move the collimator in the direction of the rows, a floodlight to irradiate the laser beam to the subject and indicate an X-ray irradiation range to the subject, and a means to change the laser beam irradiation angle so that the laser light irradiated to the subject may become nearly parallel with the X-ray having transmitted the end of the collimator. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray CT apparatus capable of indicating a scan range with a projector.

  The X-ray CT apparatus irradiates a subject with X-rays from various angles, detects X-rays transmitted through the subject, and generates an X-ray tomographic image of the subject. X-ray CT image generation by the X-ray CT apparatus (hereinafter simply referred to as scanning) is performed by rotating an X-ray tube and an X-ray detector attached to the inside of the apparatus called a gantry while opening an opening of the gantry. This is performed by irradiating the subject placed on the X-rays.

  When performing such a scan, it is necessary to perform alignment with the subject in advance so that the scan region of the subject and the X-ray irradiation range coincide. In order to perform this alignment visually in front of the actual subject, the projector irradiates the subject with laser light, and displays a reference line indicating the X-ray irradiation range on the subject. An invention is disclosed in which a user of an X-ray CT apparatus visually sets a reference line displayed on a subject so that the user can set an operation condition of the X-ray CT apparatus while checking the reference line. (For example, refer to Patent Document 1).

JP-A-9-14698

  By the way, in recent years, an X-ray CT apparatus capable of so-called multi-slice imaging in which a plurality of X-ray detectors are arranged to obtain a plurality of X-ray tomographic images in one scan has been put into practical use. When performing such multi-slice imaging, the X-ray tube has a predetermined divergence angle (hereinafter simply referred to as a cone angle) so that X-rays enter each column of the multi-row X-ray detector. Irradiate the subject with X-rays. The X-ray CT apparatus moves a collimator provided near the X-ray tube to block a part of the X-ray, thereby changing the cone angle according to the size of the scan region.

  Here, the case where the scanning range of multi-slice imaging is shown using the projector disclosed in Patent Document 1 is considered. In Patent Document 1, the projector irradiates a laser beam perpendicularly to the top plate on which the subject is placed, and displays a reference line on the subject. On the other hand, since an X-ray tube for performing multi-slice imaging irradiates X-rays with a divergence angle, the X-rays are incident obliquely on the top plate on which the subject is placed. That is, the direction of incidence on the subject differs between the laser light emitted from the projector and the X-rays incident on the end of the scan region.

  By the way, there are individual differences in the size of the subject to be diagnosed by the X-ray CT apparatus. When the subject is large, the distance between the projector or the X-ray tube and the subject is short. On the other hand, when the subject is small, the distance between the projector or the X-ray tube and the subject becomes long. Therefore, when X-rays spreading at a constant cone angle are irradiated to a large subject, the scan area becomes a small region because the distance between the subject and the X-ray tube is short, while X-rays are applied to a small subject. When the irradiation is performed, the scan area becomes a large area because the distance between the subject and the X-ray tube is long. On the other hand, the laser beam for displaying the reference line on the subject is irradiated in a direction perpendicular to the top plate on which the subject is placed, so that the reference is set at the same position regardless of the size of the subject. A line will be displayed. For this reason, when the size of the subject changes, the size of the scan area and the display position of the reference line shift, and there is a problem that the reference line cannot be irradiated to the correct position.

  Therefore, in the present invention, by controlling the X-ray transmitted through the end of the collimator and the laser light emitted from the projector to be parallel, the scan region can be correctly set even when the thickness of the subject changes. An X-ray CT apparatus that can be shown is provided.

  In order to solve the above-described problems, the present invention provides a top plate on which a subject can be placed, an X-ray tube that irradiates the subject with X-rays, and an X-ray tube that is disposed opposite to the X-ray tube in the column direction. An X-ray CT apparatus comprising an X-ray detector comprising X-ray detection elements arranged in a plurality of rows along at least a part of the X-ray provided between the X-ray tube and the detector A collimator that blocks the collimator, a collimator driving unit that moves the collimator in a column direction, a projector that irradiates the subject with a laser beam that indicates the irradiation range of the X-ray, and a laser beam that irradiates the subject. Irradiation angle changing means for changing the irradiation angle of the laser beam so as to be substantially parallel to the X-ray transmitted through the end of the collimator.

  According to the present invention, the X-ray transmitted through the end of the collimator and the laser beam emitted from the projector are controlled to be parallel. This provides an X-ray CT apparatus that can correctly indicate the scan region even when the thickness of the subject changes.

1 is a block diagram showing a configuration of an X-ray CT apparatus according to an embodiment of the present invention. Sectional drawing which shows the structure of the rotary body which concerns on embodiment of this invention. The figure which shows the structure of the collimator and projector which concern on embodiment of this invention. The figure which shows the structure of the collimator when the fan angle which concerns on embodiment of this invention changes, and a light projector. The figure which shows the angle of the fan angle and laser angle which concern on embodiment of this invention. The figure which shows the reference line displayed on the subject which concerns on embodiment of this invention. The figure which shows the structure of the collimator and projector in the structure of the conventional X-ray CT apparatus. The figure which shows the structure of a collimator and a projector when the thickness of the subject in the structure of the conventional X-ray CT apparatus changes. The figure which shows the structure of the collimator and projector which concern on the 2nd Embodiment of this invention. The figure which shows the structure of the collimator and projector which concern on the 3rd Embodiment of this invention. The figure which shows the upper surface of the collimator which concerns on the 3rd Embodiment of this invention. The figure which shows the structure of the collimator and projector which concern on the 4th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an internal configuration of an X-ray CT apparatus 1 according to the present invention.

  The control unit 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 100 includes a scan control unit 102, a reconstruction processing unit 103, an image processing unit 104, a display unit 106, a storage unit 107, and an input unit 108. The control unit 100 performs overall control of the X-ray CT apparatus 1 by processing signals supplied from the respective units and generating various control signals and supplying them to the respective units.

  The scan control unit 102 outputs an X-ray beam irradiation signal for irradiating the X-ray tube 301 with X-rays based on scan parameters input from the input unit 108 or the like when the X-ray CT apparatus 1 performs scanning. Output to the tube controller 201. Further, the scan control unit 102 rotates the rotating body 300 and moves the collimator 401 and the projector 411 based on the scan parameters such as the slice thickness, the rotation speed, and the size of the scan area input from the input unit 108 or the like. The drive signal is output to the gantry drive control unit 202. Further, the scan control unit 102 outputs a bed driving signal for moving the couchtop 500 to the bed driving control unit 203 based on scan parameters such as a scan position input from the input unit 108 and the like and a bed movement instruction.

  The reconstruction processing unit 103 generates a tomographic image of the subject P based on an X-ray detection signal output when the X-ray detector 302 detects an X-ray. Based on the back projection method, the reconstruction processing unit 103 performs back projection processing on each X-ray detection signal obtained for each rotation angle of the X-ray tube 301 and the X-ray detector 302 to generate tomographic image data. . Then, when the reconstruction processing unit 103 generates the tomographic image data, it outputs this to the image processing unit 104. Note that an X-ray detector 302 described later is configured by arranging a plurality of X-ray detection elements that detect incident X-rays along a channel direction (y direction in FIG. 1). The reconstruction processing unit 103 receives the X-ray detection signal output from each column of the X-ray detection elements constituting the X-ray detector 302 and generates tomographic image data for each column.

  Based on the instruction input from the input unit 108, the image processing unit 104 performs tomographic image data of an arbitrary cross section or rendering processing on the tomographic image data output from the reconstruction processing unit 103 by a known method. Convert to image data such as 3D image data. When the image processing unit 104 converts the image data, it outputs it to the display unit 106 or the storage unit 107.

  The display unit 106 is configured by a liquid crystal display, for example, and displays the image data output from the image processing unit 104. In addition, an operation screen for scanning the X-ray CT apparatus 1 and a scan parameter input by the input unit 108 are displayed.

  The storage unit 107 is configured by combining a storage medium such as a ROM, a RAM, a flash memory that is an electrically rewritable and erasable nonvolatile memory, and an HDD (Hard Disc Drive). The storage unit 107 stores the image data output from the image processing unit 104 and stores various applications executed by the CPU of the control unit 100.

  The input unit 108 includes, for example, a touch panel display, mechanical buttons, and the like, and receives an input made by the user of the X-ray CT apparatus 1 to the input unit 108. When the input unit 108 receives an input of a scan parameter, a scan start / stop instruction, a bed movement instruction, or the like performed by the user, the input unit 108 outputs an input signal according to the instruction performed by the user. The control unit 100 executes various processes according to the input signal output from the input unit 108.

  The X-ray tube control unit 201 receives the X-ray beam irradiation signal output from the scan control unit 102 and applies a high voltage for irradiating the X-ray tube 301 with X-rays. The application of the high voltage is performed along X-ray parameters specified by the X-ray beam irradiation signal, and the X-ray parameters specify parameters such as tube voltage, tube current, and X-ray pulse width.

  The X-ray tube 301 receives the high voltage applied from the X-ray tube control unit 201 and irradiates the X-ray detector 302 with X-rays. At this time, the X-ray tube 301 irradiates X-rays having a shape spreading in a fan shape in the column direction so that X-rays enter each column of the X-ray detector 302 configured to have a plurality of columns.

  The X-ray detector 302 detects the X-rays emitted from the X-ray tube 301 and outputs this to the reconstruction processing unit 103 as an X-ray detection signal. The X-ray detector 302 is configured by arranging a plurality of rows of semiconductor elements that detect an incident X-ray dose and generate an electrical signal along the channel direction (y direction in FIG. 1). More specifically, the X-ray detector 302 performs X-ray along the channel direction (y direction in FIG. 1) of the subject P or along the direction perpendicular to the body axis direction (z direction in FIG. 1). A row is formed by arranging the detection elements, and the row of the X-ray detection elements is further arranged along the column direction (z direction in FIG. 1) to arrange the X-ray detection elements in two dimensions. Hereinafter, the direction in which the rows of the X-ray detection elements are arranged (z direction in FIG. 1) is simply referred to as the row direction.

  The gantry drive control unit 202 receives the gantry drive signal output from the scan control unit 102, moves the collimator 401 and the projector 411, and rotates the rotating body 300. These movements and rotations are controlled based on scan parameters such as a rotation speed and a scan range specified by the input unit 108.

  The collimator 401 is a plate made of a substance that shields X-rays such as lead and tungsten. A plurality of collimators 401 are provided so as to block the irradiation direction of the X-ray tube 301 and block a part of the irradiated X-rays. As shown by the dotted lines in FIG. 1, the X-rays irradiated from the gaps of the collimator 401 spread in a fan shape in the column direction and enter the X-ray detector 302. A collimator drive motor 412 and a collimator drive gear 403, which will be described later, are connected to the collimator 401. When the gantry drive control unit 202 drives the collimator drive motor 412 and the collimator drive gear 403, the collimator 401 moves to change the region that blocks the X-ray, and the X-ray tube 301 radiates the X-ray. A spread angle with respect to the column direction (hereinafter simply referred to as a cone angle) is controlled. Specifically, the collimator 401 moves away from each other in the column direction of FIG. 1 when the cone angle is widened, and moves closer to each other when the cone angle is narrowed.

  Similarly, a collimator 430 is provided in the irradiation direction of the X-ray tube 301 in order to control a spread angle (hereinafter simply referred to as a fan angle) with respect to the X-ray scanning direction (y-axis direction in FIG. 2). . FIG. 2 is a cross-sectional view of the rotator 300 viewed from the xy plane. As shown by the dotted line in FIG. 2, the X-rays blocked by the collimator 401 spread in a fan shape in the scanning direction and enter the X-ray detector 302. A drive motor (not shown) is attached to the collimator 430, and the collimator 430 moves in the ± y direction in FIG. 2 to change the region that blocks the X-ray, thereby controlling the X-ray fan angle.

  The projector 411 is configured using, for example, a semiconductor element that emits light by applying a current, and irradiates the subject P with a line-shaped laser beam. The irradiated laser beam forms an image on the subject P and is displayed as a reference line. The projector 411 is connected to a projector rotation motor 412 to be described later, and the gantry drive control unit 202 rotates the projector rotation motor 412 to change the irradiation direction of the laser light. In this embodiment, as an example, a configuration in which the irradiation direction of laser light is changed by rotating the projector 411 itself will be described.

  However, the configuration of the present invention is not limited to this, and the irradiation direction of the laser light by rotating some components constituting the projector 411 such as a light emitting element built in the projector 411 and the direction of the irradiation port, for example. You may use the structure which changes this.

  The rotating body 300 is a cylindrical device built in the gantry 3. The rotating body 300 holds an X-ray tube 301, a collimator 401, a projector 411, an X-ray detector 302, and the like. A rotary motor is attached to the rotator 300, and when the X-ray CT apparatus 1 performs scanning, the rotator 300 receives the gantry drive instruction signal output from the gantry drive control unit 202 and drives the rotator to A rotational motion about the body axis of the specimen P is performed. As the rotator 300 rotates, the X-ray tube 301, the collimator 401, the collimator 430, the projector 411, and the X-ray detector 302 held by the rotator 300 also perform a rotational motion around the body axis of the subject P. .

  The top plate 500 is a plate-like member on which the subject P can be laid down. The top plate 500 is supported by the top plate drive unit 501, and a later-described top plate drive unit 501 moves the top plate 500 back and forth (in the z-axis direction in FIG. 1).

  The top plate driving unit 501 is a device for moving the top plate 500, which is configured by a motor (not shown) or the like. The top plate driving unit 501 is configured by attaching a belt connected to a motor to the top plate 500, for example. The position of the top plate 500 moves in conjunction with the rotation of the motor of the top plate drive unit 501. The top board driving unit 501 receives the top board driving signal output from the scan control unit 102 and moves the top board 500. For example, when the X-ray CT apparatus 1 performs scanning, the top plate driving unit 501 moves the top plate 500 into the opening of the gantry 3 in order to make the scan area of the subject P coincide with the X-ray irradiation range. In addition, the height of the top 500 is changed in order to make the rotation center of the rotating body 300 coincide with the body axis of the subject.

(First embodiment)
FIG. 3 is a diagram showing the configuration of the projector 411 in the first embodiment of the present invention. Hereinafter, the configuration and operation of the projector 411 will be described with reference to FIG.

  The projector 411 is attached to the end on the side close to the gap of the collimator 401 that emits X-rays. The projector 411 irradiates the subject P with the laser light 4110 in order to visualize the irradiation range of the X-ray 3010 and show it on the subject P. A pair of the projectors 411 is provided in the head side direction (+ z direction in FIG. 3) and the foot side direction (−z direction in FIG. 3) of the subject P, and each irradiates laser light 4110 onto the subject P. . The irradiated laser beam forms an image on the subject P and displays a reference line.

  A projector rotation motor 412 is attached to the projector 411, and the projector rotation motor 412 rotates the projector 411 around an axis parallel to the scan direction. The projector 411 rotates to change the opening angle in the column direction of the laser beam 4010 to be irradiated.

  The mechanism by which the projector rotation motor 412 rotates the projector 411 may be configured using various methods. For example, it is possible to use a configuration in which a shaft for transmitting power for rotating the projector rotation motor 412 is provided between the projector rotation motor 412 and the projector 411 and the projector 411 is rotated by the rotation of the shaft. Further, for example, it is possible to use a configuration in which the projector rotation motor 412 is directly attached to the side surface of the projector 411 and the power that the projector rotation motor 412 rotates is directly transmitted to the projector 411 to rotate the projector 411.

  On the other hand, a collimator driving gear 403 connected to the collimator driving motor 412 is provided at the end of the collimator 401 far from the gap. The collimator driving gear 403 rotates in accordance with the driving of the collimator driving motor 412 and moves the collimator 401 along the column direction. The mechanism by which the collimator driving gear 403 drives the collimator 401 may be configured using various methods. For example, one end of a belt interlocked with the rotation of the collimator driving gear 403 is attached to the collimator driving gear 403, the other end is attached to the collimator 401, and the collimator 401 is moved by transmitting the driving power of the collimator driving gear 403 to the belt. be able to. Further, for example, a configuration is used in which a plurality of grooves provided on the collimator 401 and teeth of a gear-like collimator driving gear 403 are combined, and the power to rotate the collimator driving gear 403 is directly transmitted to the collimator 401 to move the collimator 401. be able to.

  The gantry drive control unit 202 drives the collimator drive motor 412 based on the size of the scan area among the input scan parameters, and moves the collimator 401. For example, when the input scan area is smaller than the X-ray irradiation area of the X-ray 3010 irradiated at the current position of the collimator 401, the collimator drive motor 412 moves the pair of collimators 401 so as to be close to each other. . FIG. 4 shows a state when the collimators 401 are close to each other. As the gap of the collimator 401 becomes narrower, the cone angle of the X-ray 3010 emitted from the X-ray tube 301 becomes smaller, and the X-ray enters a narrower range on the subject P. Note that the projector 411 attached to the collimator 401 moves in conjunction with the movement of the collimator 401. For example, when the collimators 401 are close to each other, the projector 411 also emits the laser light 4110 from a position close to each other.

  When the collimator 401 moves and the cone angle changes, the projector rotation motor 412 rotates the projector 411 and changes the irradiation direction of the laser light 4110 according to the cone angle. More specifically, the projector rotation motor 412 rotates the projector 411 so that the irradiation direction of the laser light 4110 and the irradiation direction of the X-ray 3010 transmitted through the end of the collimator 401 are parallel to each other. FIG. 5 is a diagram showing the irradiation direction of the X-ray 3010 irradiated from the X-ray tube 301 and the irradiation direction of the laser light 4110 irradiated from the projector 411. The projector rotation motor 412 controls the rotation angle of the projector 411 so that the irradiation angle of the laser beam 4110 is inclined by the angle θ with respect to the column direction in FIG. This angle θ is controlled to be equal to the spread angle of the X-ray 3010 transmitted through the end of the collimator 401 with respect to the column direction, that is, the cone angle. Therefore, the laser light 4110 irradiated with an inclination of the angle θ has an angle parallel to the X-ray 3010 transmitted through the end of the collimator 401.

  The cone angle of the X-ray 3010 is calculated from the irradiation center of the X-ray tube 301 and the distance on the x-axis of the collimator 401 (H in FIG. 5) and the distance in the column direction (L in FIG. 5). be able to.

  In order to obtain the cone angle according to the amount of movement of the collimator 401, the storage unit 107 stores in advance a table or function that associates the position of the collimator 401 with the cone angle of the X-ray 3010. The projector rotation motor 412 rotates the projector 411 based on the position information of the collimator 401 and the cone angle of the X-ray 3010 obtained based on the table or function stored in the storage unit 107, and the irradiation direction of the laser beam 4110. To change.

  FIG. 6 is a diagram illustrating a state of the reference line displayed on the subject P. The laser beam 4110 displays a reference line of one character parallel to the scan direction (y-axis direction in FIG. 6) on the subject P. The projector 411 changes the irradiation direction and position of the laser light 4110 in conjunction with the operations of the projector rotation motor 412 and the collimator driving motor 412 described above, and changes the display position of the reference line according to the cone angle of the X-ray 3010. More specifically, the projector 411 shows two reference light beams so as to indicate an end on the head side (+ z direction in FIG. 6) and an end on the foot side (−z direction in FIG. 6) in the irradiation range of the X-ray 3010. Change the display position. The user of the X-ray CT apparatus 1 visually recognizes the reference light displayed on the subject P and visually recognizes the position where the irradiation range of the X-ray 3010 is located.

(Subject thickness and reference line irradiation position)
As described above, the irradiation direction of the laser beam 4110 irradiated by the projector 411 is controlled to be parallel to the X-ray 3010 that passes through the end of the collimator 401. By controlling the irradiation direction of the laser light 4110 to be parallel, the projector 411 can display the reference line at the correct position even when the thickness of the subject P changes.

  On the other hand, in the conventional X-ray CT apparatus shown in the prior art document 1 and the like, the irradiation direction of the laser light 4010 is different from the direction of the X-ray 3010 that passes through the end of the collimator 401. The position of the reference line and the irradiation range of the X-ray 3010 are shifted, and the reference line cannot be displayed at the correct position. FIG. 7 is a diagram showing the irradiation position of the X-ray 3010 and the laser beam 4110 on the subject P when the laser beam 4110 is irradiated perpendicularly to the subject P in the conventional X-ray CT apparatus. In FIG. 7, the shape of the subject P is shown in a simplified manner for easy explanation.

  FIG. 7A shows the irradiation position of the X-ray 3010 and the laser beam 4110 when the subject P is thin. For example, as shown in FIG. 7 (a), the end on the head side (+ z direction in FIG. 7) and the end on the foot side (−z direction in FIG. 7) in the irradiation range of the X-ray 3010, and the display position of the reference light And the position of the projector 411 is adjusted. FIG. 7B shows the irradiation position of the X-ray 3010 and the laser beam 4110 when the subject P is thick. Since the X-ray 3010 is incident on the subject P in an oblique direction, the irradiation range of the X-ray 3010 on the subject P is larger than that shown in FIG. It narrows and the end on the head side approaches the end on the foot side. Therefore, as the thickness of the subject P increases, the irradiation position of the laser light 4110 irradiated vertically and the irradiation range of the X-ray 3010 shift, and the projector 411 cannot display the reference line at the correct position. Thus, when the X-ray 3010 is incident on the subject P obliquely, the irradiation range of the X-ray 3010 changes according to the change in the thickness of the subject P.

  FIG. 8 shows the subject P when the X-ray CT apparatus 1 according to the present invention is used to control the irradiation direction of the laser light 4110 to be parallel to the X-ray 3010 that passes through the end of the collimator 401. The irradiation position of the X-ray 3010 and the laser beam 4110 above is shown. For example, as shown in FIG. 8A, an X-ray 3010 that matches the positions of the head-side and foot-side ends of the X-ray 3010 and the display position of the reference light and transmits through the end of the collimator 401. Assume that the projector 411 is adjusted and attached so that the irradiation direction of the laser beam 4110 is parallel to the irradiation direction. FIG. 8B shows the irradiation position of the X-ray 3010 and the laser beam 4110 when the subject P is thick. Since the X-ray 3010 that passes through the end of the collimator 401 and the laser light 4110 are incident on the subject P at a parallel angle, the reference line is irradiated even if the thickness of the subject P changes. Can be displayed correctly at the end of the.

  With the above configuration, the projector 411 controls the irradiation angle of the laser light 4110 so as to be parallel to the irradiation angle of the X-ray 3010 that passes through the end of the collimator 401. Thus, even when the thickness of the subject P changes and the irradiation range of the X-ray 3010 on the subject P changes, the laser beam 4110 indicating the irradiation range is irradiated to the correct position, and the reference line is applied. It can be projected onto the specimen P.

(Second Embodiment)
FIG. 9 is a diagram showing a configuration of a projector 411 according to the second embodiment of the present invention. Hereinafter, the configuration and operation of the projector 411 will be described with reference to FIG.

  In the second embodiment, a projector support plate 404 is provided below the collimator 401, and the projector 411 is attached on the projector support plate 404. A projector support plate drive gear 405 is attached to the projector support plate 404, and the projector support plate 404 moves in the row direction in FIG. 9 in accordance with the rotation of the projector support plate drive gear 405. The projector support plate drive gear 405 is connected to the collimator drive motor 412 and operates in conjunction with the rotation of the collimator drive gear 403.

  The projector support plate drive gear 405 that rotates in conjunction with the rotation of the collimator drive gear 403 is provided such that its rotation diameter is larger than that of the collimator drive gear 403. Therefore, when the collimator drive motor 412 rotates the collimator drive gear 403 and the projector support plate drive gear 405 by the same number of rotations, the projector support plate 404 moves a longer distance than the collimator 403. The rotation diameter of the projector support plate drive gear 405 is determined based on the height difference between the collimator 401 and the projector 411 on the x axis in FIG.

  The mechanism for driving the projector support plate 404 by the projector support plate drive gear 405 may be configured using various methods. For example, one end of the belt interlocked with the rotation of the projector support plate drive gear 405 is attached to the projector support plate drive gear 405, and the other end is attached to the projector support plate 404, thereby transmitting the rotational power of the projector support plate drive gear 405 to the belt. A configuration in which the projector support plate 404 is moved can be used. Further, for example, a plurality of grooves provided on the projector support plate 404 and teeth of the gear-like projector support plate drive gear 405 are combined, and the power for rotating the projector support plate drive gear 405 is transmitted to the projector support plate 404 to transmit the projector. A configuration in which the support plate 404 is moved can be used.

  Similarly to the configuration described in the first embodiment, a projector rotation motor 412 is attached to the projector 411, and the projection direction of the laser light 4110 is changed by rotating the projector 411 according to the cone angle.

  The operation when the collimator 401 moves and the cone angle changes will be described below with reference to FIG. For example, when the cone angle is widened based on the scan parameter input by the input unit 108 or the like, the gantry drive control unit 202 drives the collimator drive motor 402 to rotate the collimator drive gear 403 and separate the collimators 401 from each other. . At this time, the projector support plate drive gear 405 connected to the collimator drive motor 402 also rotates in conjunction with the projector support plate 404 to be separated from each other.

  Further, the gantry drive control unit 202 rotates the projector 411 based on the position information of the moved collimator 401 and the cone angle of the X-ray 3010 obtained based on the table or function stored in the storage unit 107. The projector 411 rotates to change the irradiation direction of the laser light 4110 in a direction parallel to the X-ray 3010 that passes through the end of the collimator 401.

  With the above operation, the irradiation position of the laser beam 4110 irradiated by the projector 411 coincides with the end of the irradiation range of the X-ray 3010, and the user visually recognizes the reference line displayed on the subject P and observes the X-ray 3010. Check the irradiation range.

  Note that the projector 411 is at a lower position on the x-axis in FIG. 9 than the collimator 401. Therefore, in order for the laser light 4110 irradiated by the projector 411 to approach the X-ray 3010 that passes through the end of the collimator 401, the distance at which the projector support plate 404 is separated (L ′ in FIG. 9) is separated from the collimator 401. This distance must be larger than the distance (L in FIG. 9).

  Therefore, in the present invention, the rotation diameter of the projector support plate drive gear 405 is provided so as to exceed the rotation diameter of the collimator drive gear 403. As a result, the projector support plate 404 that moves in conjunction with the collimator 403 moves a longer distance than the collimator 403. Therefore, even when the projector 411 is at a position lower than the collimator 403, the laser light 4110 can be irradiated close to the X-ray 3010 that passes through the end of the collimator 401.

  According to the second embodiment, the projector 411 can be moved independently of the collimator 401 by attaching the projector 411 to the projector support plate 404. Thereby, the laser beam irradiation position of the projector 411 can be controlled more finely, and the reference line can be displayed at the correct position. Further, according to the second embodiment, the collimator 401 and the projector support plate 404 are moved by the collimator drive motor 412 connected to and connected to both. Since there is no need to attach separate motors to the collimator 401 and the projector support plate 404, the number of parts constituting the X-ray CT apparatus 1 can be reduced, and the X-ray CT apparatus 1 can be configured more easily.

(Third embodiment)
FIG. 10 is a diagram showing a configuration of a projector 411 according to the third embodiment of the present invention. Hereinafter, the configuration and operation of the projector 411 will be described with reference to FIG.

  In the third embodiment, a projector support plate 404 is provided on the upper part of the collimator 401, and the projector 411 is attached on the projector support plate 404. In addition, a slit 406 is provided at the end of the collimator 401 close to the gap. FIG. 11 shows a top view of the collimator 401 viewed from the x direction. The laser light 4110 irradiated by the projector 411 passes through the slit 406 provided in the collimator 401 and is irradiated onto the subject P. In addition, although the slit 406 shows the example provided in hole shape in the collimator 401, the shape of the slit 406 is not limited to what was described here. For example, a concave notch may be provided at the end near the gap of the collimator 401 and this notch may be used as the slit 406.

  Further, an X-ray shielding plate 407 is provided at the end of the collimator 401 on the side close to the gap. The X-ray shielding plate 407 is attached in a parallel direction on the xy plane, and prevents the X-ray 3010 emitted from the X-ray tube 301 from entering the subject P through the slit 406.

  Further, the projector support plate 404 is provided with a projector support plate drive gear 405. The projector support plate 404 moves in the column direction in FIG. 10 in accordance with the rotation of the projector support plate drive gear 405. The projector support plate drive gear 405 is connected to the collimator drive motor 412 and operates in conjunction with the rotation of the collimator drive gear 403.

  In contrast to the configuration of the projector 411 described in FIG. 9, in the third embodiment, the projector 411 is provided at a position higher than the collimator 401 on the x-axis in FIG. 11. Therefore, the distance that the projector 411 moves needs to be shorter than the distance that the collimator 401 moves. Therefore, the projector support plate drive gear 405 that rotates in conjunction with the rotation of the collimator drive gear 403 in the third embodiment is provided so that the rotation diameter is smaller than that of the collimator drive gear 403. Therefore, when the collimator drive motor 412 rotates the collimator drive gear 403 and the projector support plate drive gear 405 by the same number of rotations, the projector support plate 404 moves a shorter distance than the collimator 403. The rotation diameter of the projector support plate drive gear 405 is determined based on the height difference between the collimator 401 and the projector 411 on the x axis in FIG.

  Similarly to the configuration described in the first embodiment, a projector rotation motor 412 is attached to the projector 411, and the projection direction of the laser light 4110 is changed by rotating the projector 411 according to the cone angle.

  The operation when the collimator 401 moves and the cone angle changes will be described below. For example, when the cone angle is widened based on the scan parameter input by the input unit 108 or the like, the gantry drive control unit 202 drives the collimator drive motor 412 to rotate the collimator drive gear 403 and separate the collimators 401 from each other. . At this time, the projector support plate drive gear 405 connected to the collimator drive motor 412 also rotates in conjunction with the projector support plate 404 to be separated from each other.

  Further, the gantry drive control unit 202 rotates the projector 411 based on the position information of the moved collimator 401 and the cone angle of the X-ray 3010 obtained based on the table or function stored in the storage unit 107. The projector 411 rotates to change the irradiation direction of the laser light 4110 in a direction parallel to the X-ray 3010 that passes through the end of the collimator 401.

  With the above operation, the irradiation position of the laser beam 4110 irradiated by the projector 411 coincides with the end of the irradiation range of the X-ray 3010, and the user visually recognizes the reference line projected on the subject P and observes the X-ray 3010. Check the irradiation range.

  According to the third embodiment, the mechanism for irradiating the laser beam 4110 can be concentrated on the upper part of the collimator 4010. As a result, it is possible to mount the projector 411 that projects the reference line in the X-ray CT apparatus 1 while keeping the opening of the gantry 3 wide without adding new parts below the collimator 401.

(Fourth embodiment)
FIG. 12 is a diagram showing a configuration of a projector 411 according to the fourth embodiment of the present invention. Hereinafter, the configuration and operation of the projector 411 will be described with reference to FIG.

  In the embodiment of FIG. 4, a mirror 421 is provided at the end of the collimator 401 on the side close to the gap, instead of the projector 411. The projector 411 is provided below the collimator 401, and the projector 411 emits laser light toward the mirror 421.

  In addition, a mirror rotation motor 422 is connected to the mirror 421. The mirror rotation motor 422 changes the angle of the mirror 421 with respect to the subject P in accordance with the gantry drive signal output from the gantry drive control unit 202.

  The operation when the collimator 401 moves and the cone angle changes will be described below. For example, when the cone angle is widened based on the scan parameter input by the input unit 108 or the like, the gantry drive control unit 202 drives the collimator drive motor 412 to rotate the collimator drive gear 403 and separate the collimators 401 from each other. .

  Further, the gantry drive control unit 202 rotates the mirror 421 based on the positional information of the moved collimator 401 and the cone angle of the X-ray 3010 obtained based on the table or function stored in the storage unit 107. The laser light 4110 emitted from the projector 411 enters the mirror 421, and the mirror 421 irradiates the subject P with the laser light 4110. At this time, the rotation angle of the mirror 421 is controlled so that the laser light 4110 irradiated to the subject P is parallel to the X-ray 3010 that passes through the end of the collimator 401.

  Through the above operation, the laser light 4110 emitted by the projector 411 is reflected by the mirror 421, the irradiation position of the reflected laser light 4110 coincides with the end of the X-ray 3010 irradiation range, and the user is placed on the subject P. The projected reference line is visually confirmed to confirm the irradiation range of the X-ray 3010.

  In the present embodiment, it has been described that the angle of the mirror 421 is controlled in order to change the irradiation angle of the laser light 4110. However, the configuration of the present invention is not limited to this, and the angle of the mirror 421 is fixed and attached to the collimator 401, and the mirror rotation motor 422 is attached to the projector 411. The angle of the laser beam 4110 applied to the subject P may be controlled to be equal to the cone angle by rotating the projector 411 and changing the incident angle of the laser beam 4110 to the mirror 421.

  According to the fourth embodiment, since the mirror 421 is lighter than the projector 411, the power required to drive the collimator drive motor 412 can be reduced as compared with the first embodiment. By reducing the drive power of the collimator drive motor 412, the collimator drive motor 412 can be made compact and the opening of the gantry 3 can be widened.

  In each of the embodiments, it has been described that the irradiation angle of the laser beam 4110 and the irradiation angle of the X-ray 3010 transmitted through the end of the collimator 401 are controlled to be parallel according to the present invention. However, the irradiation angle of the laser beam 4110 does not have to be completely parallel to the irradiation angle of the X-ray 3010 geometrically. For example, even if the irradiation angle of the laser light 4110 is slightly shifted due to an error in the mounting angle of the projector 411 or the projector rotation motor 412, the irradiation range of the X-ray 3010 can be visually recognized using the reference light. Alternatively, the attachment angle of the projector 411 and the projector rotation motor 412 may be changed so that the irradiation angle of the laser light 4110 is slightly smaller than the irradiation angle of the X-ray 3010. By reducing the irradiation angle of the laser beam 4110, the laser beam 4110 and the X-ray 3010 can be brought closer to each other, and the position of the reference line can be brought closer to the end of the scan range.

In addition, this invention is not limited to what was disclosed by the said embodiment, A various invention can be formed with a proper combination of the some component currently disclosed by the said embodiment. For example, in the present embodiment, the collimator driving motor 402 and the projector rotation motor 412 are provided separately, and each of them moves the collimator 401 and rotates the projector 411. However, instead of providing the projector rotation motor 412, a projector rotation gear having a rotation diameter different from that of the collimator driving gear 403 is attached to the projector 411. The projector rotating gear may be rotated in conjunction with the rotation of the collimator driving motor 402, and the irradiation direction of the laser light 4110 of the projector 411 may be controlled by the rotation of the projector rotating gear. Further, for example, in the third embodiment, the collimator 401 and the projector support plate 404 are described as being connected to the same collimator drive motor 402, but another projector support plate drive motor is provided to drive the projector support plate 404. It doesn't matter. Further, for example, as long as the position of the projector 411 is on the rotator 300, the projector 411 may be arranged at another position instead of the vicinity of the X-ray tube 301. Further, for example, some components may be deleted from all the components shown in the embodiment. Or you may combine the component covering a different Example suitably.

1 X-ray CT apparatus 100 control unit 102 scan control unit 103 reconstruction processing unit 104 image processing unit 106 display unit 107 storage unit 108 input unit 201 X-ray tube control unit 202 gantry drive control unit 203 bed driving control unit 300 rotator 301 X-ray tube 302 X-ray detector 401 Collimator 402 Collimator drive motor 403 Collimator drive gear 404 Projector support plate 405 Projector support plate drive gear 406 Slit 407 X-ray shielding plate 411 Projector 412 Projector rotation motor 421 Mirror 422 Mirror rotation motor 430 Collimator 500 Top plate 501 Top plate drive unit

Claims (6)

A top plate on which a subject can be placed, an X-ray tube that irradiates the subject with X-rays, and an X-ray that is arranged opposite to the X-ray tube and arranged in a plurality of rows along the column direction In an X-ray CT apparatus comprising an X-ray detector comprising a detection element,
A collimator provided between the X-ray tube and the detector and blocking at least a part of the X-ray;
Collimator driving means for moving the collimator along a column direction;
A projector that irradiates the subject with laser light indicating the X-ray irradiation range;
X-rays having irradiation angle changing means for changing the irradiation angle of the laser beam so that the laser beam irradiated to the subject is substantially parallel to the X-ray transmitted through the end of the collimator CT device. 2. The X-ray CT apparatus according to claim 1, wherein the irradiation angle changing unit is attached to the projector and changes the irradiation angle of the laser light in accordance with the movement of the collimator. A projector support member to which the projector is attached;
The X-ray CT apparatus according to claim 2, wherein the collimator driving device moves the projector support member along a column direction along with the movement of the collimator. The projector support member and the projector are provided between the X-ray tube and the collimator, and the collimator further includes a slit that transmits laser light emitted from the projector, and is attached to the collimator, The X-ray CT apparatus according to claim 3, further comprising an X-ray shielding plate that shields at least a part of the X-rays irradiated from the tube toward the slit. The irradiation angle changing means includes a mirror that reflects the laser beam irradiated from the projector and irradiates the subject.
The irradiation angle changing means is attached to the mirror, and rotates the mirror based on the movement of the collimator to change the irradiation angle of the laser beam irradiated to the subject. The X-ray CT apparatus described. A top plate on which a subject can be placed, an X-ray tube that irradiates the subject with X-rays, and an X-ray that is arranged opposite to the X-ray tube and arranged in a plurality of rows along the column direction In an X-ray CT apparatus comprising an X-ray detector comprising a detection element,
A collimator provided between the X-ray tube and the detector and blocking at least a part of the X-ray;
Collimator driving means for moving the collimator along a column direction;
A projector that is provided between the X-ray tube and the detector and irradiates the subject with a laser beam indicating an irradiation range of the X-ray;
An X-ray CT apparatus comprising: an irradiation angle changing unit that changes the irradiation angle of the laser beam in correspondence with the movement of the collimator.

Images